Short-range correlation effects on the nuclear matrix element of neutrinoless double-βdecay

We report the results of a calculation of the nuclear matrix element of neutrinoless double-β decay of Ca48, carried out taking into account nucleon-nucleon correlations in both coordinate and spin space. Our numerical results, obtained using nuclear matter correlation functions, suggest that inclusion of correlations may lead to a ∼20% decrease of the matrix element, with respect to the shell-model prediction. This conclusion is supported by the results of an independent calculation, in which correlation effects are taken into account using the spectroscopic factors of Ca48, obtained from an ab initio many-body approach, to renormalize the shell-model states.